(a) Field of the Invention
The present invention relates to a writing instrument, and more specifically to an in chamber pressure enhancing control device for a writing instrument which can be pressed to increase the inside pressure of the ink chamber of the writing instrument.
(b) Description of the Prior Art
A writing instrument having an ink chamber in it is generally equipped with means for enhancing the inside pressure of the ink chamber. Japanese Utility Model No. 5-32235 discloses the use of a pen cap to force air into the ink chamber. The air inside the pen cap is compressed and forced through the writing tip into the ink chamber, when the pen cap is closed on the barrel of the writing instrument. If the inside pressure of the ink chamber is insufficient during writing, the user must stop writing, then attach the pen cap to the barrel of the writing instrument, and then start writing again after removal of the pen cap from the barrel. This operation procedure is complicated. Japanese Utility Model No. 60-90160 discloses a similar design. This design enables air to be forced through the writing tip into the ink chamber to increase the inside pressure of the ink chamber, when the pen cap is closed on the barrel of the writing instrument.